Forced frequency ignition system for an internal combustion engine

ABSTRACT

An ignition system for an internal combustion engine has a power source, a transformer having first and second primary windings and a secondary winding, a connector extending from the secondary winding and adapted so as to connect with a terminal of the spark plug of the internal combustion engine, and electronic spark timing circuit cooperative with the transformer so as to activate and deactivate voltage to the first and second primary windings. The first and second primary windings are connected to the power source such that the transformer produces an alternating voltage output from the secondary winding of between 1 kHz and 100 kHz and a voltage of at least 20 kV. A forced push-pull inverter is cooperative with the electronic spark timing circuit so as to fix a frequency of voltage to the first and second primary windings.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

INCORPORATION-BY-REFERENCE OF MATERIALS SUBMITTED ON A COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to internal combustion engines. Moreparticularly, the present invention relates to electrical ignitionapparatus that are used for the igniting the fuel within the internalcombustion engine. More particularly, the present invention relates toignition coils which apply an AC voltage for the ignition of the sparkplug within the internal combustion engine.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 37 CFR 1.98

Most internal combustion engines have some type of an ignition circuitto generate a spark in the cylinder. The spark causes combustion of thefuel in the cylinder to drive the piston and the attached crankshaft.Typically, the engine includes a plurality of permanent mount magnetsmounted on the flywheel of the engine and a charge coil mounted on theengine housing in the vicinity of the flywheel. As the flywheel rotates,the magnets pass the charge coil. A voltage is thereby generated on thecharge coil and this voltage is used to charge a high-voltage capacitor.The high-voltage charge on the capacitor is released to the ignitioncoil by way of a triggering circuit so as to cause a high-voltage,short-duration electrical spark across the spark gap of the spark plugand ignite the fuel in the cylinder. This type of ignition is called acapacitive discharge ignition.

The design of standard reciprocating internal combustion engines whichuse ignition coils to initiate combustion have, for years, utilizedcombustion chamber shapes and spark plug placements which were heavilyinfluenced by the need to reliably initiate combustion using only asingle short-duration spark having a relatively low intensity. In recentyears, however, increased emphasis has been placed on fuel efficiency,completeness of combustion, exhaust cleanliness, and reduced variabilityin cycle-to-cycle combustion. This emphasis has meant that the shape ofthe combustion chamber must be modified and the ratio of the fuel-airmixture changed. In some cases, a procedure has been used whichdeliberately introduces strong turbulence or a rotary flow of thefuel-air mixture at the area where the spark plug electrodes are placed.This often causes an interruption or “blowing out” of the arc. This hasplaced increasing demands on the effectiveness of the combustioninitiation process. It is been found highly preferable, in suchapplications, to have available an arc which may be sustained for asmuch as four to five milliseconds. Efforts to effectuate this idea haveresulted in various innovations identified in several patents.

For example, U.S. Pat. No. 5,806,504, issued on Sep. 15, 1998 to Frenchet al., teaches an ignition circuit for an internal combustion engine inwhich the ignition circuit includes a transformer having a secondarywinding for generating a spark and having first and second primarywindings. A capacitor is connected to the first primary winding toprovide a high-energy capacitive discharge voltage to the transformer. Avoltage regulator is connected to the secondary primary winding forgenerating an alternating current voltage. A control circuit isconnected to the capacitor and to the voltage generator for providingcontrol signals to discharge the high-energy capacitive dischargevoltage to the first primary winding and for providing control signalsto the voltage generator so as to generate an alternating currentvoltage.

U.S. Pat. No. 4,998,526, issued on Mar. 12, 1991 to K. P. Gokhae,teaches an alternating current ignition system. The system appliesalternating current to the electrodes of a spark plug to maintain an arcat the electrodes for a desired period of time. The amplitude of the arccurrent can be varied. The alternating current is developed by aDC-to-AC inverter that includes a transformer that has a center-primaryand a secondary that is connected to the spark plug. An arc is initiatedat the spark plug by discharging a capacitor to one of the windingportions at the center-primary. Alternatively, the energy stored in aninductor may be supplied to a primary winding portion to initiate anarc. The ignition system is powered by a controlled current source thatreceives input power from a source of direct voltage, such as a batteryon the motor vehicle.

In each of these prior art patents, the devices used dual mechanisms inwhich a high-energy discharges were supplemented with a low-energyextending mechanism. The method of extending the arc, however, presentsproblems to the end-user. First, the mechanism is, by nature,electronically complex in that multiple control mechanisms must bepresent either in the form of two separate arc mechanisms. Secondly, nomethod is presented for automatically sustaining the arc under acondition of repeated interruptions. Additionally, these mechanisms donot necessarily provide for a single functional-block unit of low massand small size which contains all of the necessary functions within.

U.S. Pat. No. 6,135,099, issued on Oct. 24, 2000 to T. Marrs, disclosesan ignition system for an internal combustion engine that comprises atransformer means having a primary winding adapted to be connected to apower supply and having a secondary winding adapted be connected to aspark plug. The transformer serves to produce an output from thesecondary winding having a frequency of between 1 kHz and 100 kHz and avoltage of at least 20 kV. A controller is connected to the transformerso as to activate and deactivate the output of the transformer meansrelative to the combustion cycle. The transformer serves to produce theoutput having an alternating current with a high-voltage sine wavereaching at least 20 kV. A voltage regulator is connected to the powersupply into the transformer so as to provide a constant DC voltage inputto the transformer. The transformer produces power of constant wattagefrom the output of the secondary winding during the activation by thecontroller. The controller is connected to the transformer so as toallow the transformer to produce an arc of controllable duration acrossthe electrode of the spark plug. This duration can be between 0.5milliseconds and 4 milliseconds. A battery is connected the primarywinding of the transformer. The battery produces a variable voltage ofbetween 5 and 15 volts.

It is an object of the present invention to provide an ignition systemwhich includes a transformer which is of a small enough size to bemounted directly on to the spark plug.

It is another object of the present invention to provide an ignitionsystem which allows for simple radio frequency shielding so as toprevent radio frequency interference in the electrical system of thevehicle.

It is another object of the present invention to provide an ignitionsystem which delivers constant wattage during the entire burn time.

It is another object of the present invention to provide an ignitionsystem which enhances the ability to fire cold fuel at start-up.

It is a still another object of the present invention to provide anignition system which delivers alternating current to the spark plug soas to greatly reduce spark plug gap erosion.

It is a further object of the present invention to provide an ignitionsystem which provides for an adjustable arc duration on the electrode ofthe spark plug.

It is still another object of the present invention to provide anignition system which can be used consistently and effectively withvariable input voltage from the vehicle battery.

It is still a further object of the present invention to provide anignition system which includes means for sensing the voltage and currentat the output of the ignition module for the purpose of assessingconditions within the cylinder.

It is still a further object of the present invention to provide anignition system which is easy-to-use, easy-to-manufacture and relativelyinexpensive.

These and other objects and advantages of the present invention willbecome apparent from a reading of the attached specification andappended claims.

BRIEF SUMMARY OF THE INVENTION

The present invention is an ignition system for an internal combustionengine. The ignition system includes a power source, a transformerhaving first and second primary windings and a secondary winding, aconnector extending from the secondary winding and adapted to connectwith a terminal of the spark plug of the internal combustion engine, andan electronic spark timing circuit cooperative at the transformer so asto activate and deactivate voltage to the first and second primarywindings. The first and second primary windings are connected to thepower source such that the transformer produces an alternating voltageoutput from the secondary winding of between 1 kHz and 100 kHz and avoltage of at least 20 kV.

A forced push-pull inverter is cooperative with the electronic sparktiming circuit so as to fix a frequency of current to the first andsecond primary windings. The fixed frequency is between 1 kHz and 100kHz. The forced push-pull inverter includes an astable oscillator.

A gate-driven IC is cooperative with the electronic spark timing circuitso as to transmit voltage relative to a timing pulse of the electronicspark timing circuit. A first field effect transistor (FET) is connectedto an output of the gate-driven IC. The first FET is switchable so as totransmit the alternating voltage to the first primary winding. A secondFET is connected to an output of the gate driven IC. The second FET isswitchable so as to transmit the alternating voltage to the secondprimary winding.

The engine control module passes a square wave of voltage to theelectronic spark timing circuit. The electronic spark timing circuitproduces a pulse off of the falling edge of the square wave. The squarewave ranges from 0 volts to 5 volts. A spark is generated to thesecondary winding from the electronic spark timing circuit when thesquare wave falls from 5 volts to 0 volts. The alternating voltageoutput of the secondary winding is a spark having an arc that has acontinuous arc duration of between one-half millisecond and fivemilliseconds.

A voltage regulator circuit is electrically connected between the powersource and the electronic spark timing circuit so as to step downvoltage from the power source. The voltage regulator establishes areference voltage of 8 volts. The gate-driven IC inverts voltage so asto ultimately cause the first FET and the second FET to firealternately. A transient voltage suppressor is electrically connectedbetween the power source and electronic spark timing circuit. In thepresent invention, the power supply includes a battery having a voltageof between 5 volts and 15 volts.

In accordance with a second aspect of the present invention, there isprovided an ignition system for an internal combustion engine thatincludes a transformer having a primary winding adapted to be connectedto a power supply and a secondary winding. The transformer produces analternating voltage output from the secondary winding having a frequencyof between 1 kHz and 100 kHz and a voltage of at least 20 kV. Thetransformer includes an oscillator-based push-pull inverter connected tothe primary winding. A connector extends from the secondary winding ofthe transformer and is adapted to connect with a terminal of a sparkplug of the internal combustion engine. A controller is interconnectedto the transformer so as to activate and deactivate the output of thetransformer.

In accordance with a third aspect of the present invention, there isprovided an ignition system for an internal combustion engine thatincludes a transformer having a primary winding adapted to be connectedto a power supply and a secondary winding. The transformer produces anoutput from the secondary winding of an alternating voltage having afrequency of between 1 kHz and 100 kHz. A single spark plug is connectedto the secondary winding of the transformer. A controller isinterconnected to the transformer so as to place the transformer in anactive state and in an inactive state. The transformer passes thevoltage to the single spark plug in the active state.

In accordance with a fourth aspect of the present invention, there isprovided an ignition system for an internal combustion engine includes abattery, a voltage regulator connected to the battery and adapted topass a constant DC voltage is an output therefrom, a plurality oftransformers each having a primary winding on a secondary winding inwhich the primary winding is connected to the voltage regulator so as toreceive constant DC voltage therefrom. A spark plug is connected to thesecondary winding of each of the transformers. Each of the transformersserves to pass power of constant wattage to the spark plug.

In accordance with a fifth aspect of the present invention, there isprovided an ignition system for an internal combustion engine thatcomprises a transformer having a primary winding adapted be connected toa power supply and has a secondary winding. A spark plug is connected tothe secondary winding of the transformer. The spark plug has anelectrode formed thereon so as to allow a spark to pass therefrom. Thetransformer passes voltage of at least 20 kV to the spark plug. Thevoltage that is passed to the spark plug by the transformer has analternating voltage of between 1 kHz and 100 kHz. The controller isconnected to the transformer. The controller places the transformer inan active state and in an inactive state. The active state correspondsto a duration of the spark across the electrode. This duration isbetween 0.5 milliseconds and 4 milliseconds.

In still a further aspect of the present invention, there is provided anignition system for an internal combustion engine which includes atransformer having a primary winding adapted to be connected to a powersupply and a secondary winding adapted to be connected to a spark plug.The transformer serves to produce an output from the secondary windinghaving a frequency of between 1 kHz and 100 kHz and a voltage of atleast 20 kV.

A controller is connected to the transformer so as to activate anddeactivate the output of the transformer relative to the combustioncycle. The transformer serves to produce the output having analternating voltage with a high-voltage sine wave reaching at least 20kV. A power-boost voltage regulator is connected to the power supply andto the transformer so as to provide a constant DC voltage input to thetransformer. The transformer produces power of constant wattage from theoutput of the secondary winding during the activation by the controller.The controller is connected to the transformer so as to allow thetransformer to produce an arc of controllable duration across theelectrode of the spark plug. Ideally, this duration can be selectedbetween 0.5 milliseconds and 4 milliseconds. A battery is connected tothe input of the power-boost voltage regulator. The battery produces avariable voltage of between 5 and 15 V.

In the present invention, the secondary winding includes an outputsecondary winding having a connector extending therefrom. This outputsecondary winding can have, if desired, a current sensor attachedthereto and connected to the controller so as to sense current throughthe output secondary winding. A sensing secondary winding can be, ifdesired, connected to the controller so as to sense a voltage of theoutput of the transformer. The transformer includes an inverter forconverting the output to an alternating voltage. In the presentinvention, the specific inverter which is used as a form of push-pulloscillator inverter connected to the primary winding of the transformer.The power-boost voltage regulator in the present invention includes aswitch regulator integrated circuit connected to an energy storageinductor and to a switching transistor. The switch regulator integratedcircuit (IC) receives a variable voltage from the power supply orbattery. The switch regulator IC provides a regulated voltage of between15 and 50 volts to the transformer. A voltage input is connected to theswitch regulator integrated circuit for reducing the fixed voltage witha proportional positive voltage.

In the preferred embodiment of the present invention, the transformer isdirectly connected to the spark plug. An electrical line will extendfrom the transformer to the controller which is mounted at a locationaway from the spark plug. The battery associated with the internalcombustion engine has a power supply line extending to the ignitioncontroller. The ignition controller will pass a regulated voltage fromthe battery to the transformer. The ignition controller can be in thenature of a series of digital/analog control circuits,microprocessor(s), custom-integrated circuits and associated discretedevices, or similar electronics.

The present invention offers a number of advantages over various priorart systems. The present invention utilizes a very small-sizedhigh-voltage transformer. This is the result of the high frequency ofthe operation and the fact that the transformer boosts a relatively highvoltage input rather than a battery input. The transformer can be smallenough to mount directly on top of the spark plug so as to create apackage several times smaller and lighter than conventional systems.This further allows for easy radio frequency shielding as well aspreventing radio frequency interference in the electrical systems, aswell as in the radio of the vehicle. The high-frequency operation allowsfor a smaller ferrite core and the high input voltage allows for asmaller turns ratio and consequently fewer turns of wire on thesecondary. It is believed that the transformer can utilize a coil whichis 1.25 inches in diameter of only 2.5 inches long.

The present invention delivers constant wattage during the entire arcduration or burn time. A normal ignition system fires with maximumwattage in the first 100 microseconds and then exponentially decays tozero. The present invention delivers enough voltage and power to re-firean extinguished spark throughout the entire “on” time. This is of greatbenefit in firing cold fuel at start-up (cold starting) when the fuel isnot warm enough to fully vaporize.

The present invention utilizes alternating current to the spark plug soas to greatly reduce spark plug gap erosion. Experience has shown thatmaterial is removed from the anode and deposited on the cathode, or viceversa, during the operation of normal ignition systems. The removal ofmaterial will depend upon the flow direction of the DC current in thespark plug gap. Under certain circumstances, spark plug gaps can erodefrom 20,000 volt gaps to 35,000 volt gaps over time in conventionalsystems.

In the present invention, the arc duration is controllably adjustablefrom between 0.5 milliseconds to 4 milliseconds by simply changing atiming resistor/capacitor or discharge rate, or changing during theduration of the electronic spark timing input timing signal itself. Inactual application, the arc duration can be 4 milliseconds during coldstarting and reduced to 0.5 milliseconds during normal operation.Additional timer circuits can also be used so as to produce multiple ACbursts for a given electronic spark timing input signal, as desired.This serves to reduce spark plug wear and reduce the power requirementson the batteries. This adjustment can be done automatically by thecontroller in relation to engine temperature or other input variables.The power boost voltage regulator provided in the present inventionallows the present invention to operate satisfactorily over a range of 5volts to 15 volts of input. This variable input voltage is the result ofthe use of conventional automotive batteries.

This foregoing Section is intended to describe, with particularity, thepreferred embodiments of the present invention. It is understood thatvariations to these preferred embodiments can be made within the scopeof the present claims. As such, this Section should not be construed aslimiting of the broad scope of the present invention. The presentinvention should only be limited by the following claims and their legalequivalents.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram, with appropriate connection shown, of apreferred embodiment of the present invention.

FIG. 2 is a schematic diagram of the electronics associated with thecircuitry of the ignition system of the present invention.

FIG. 3 is a block diagram showing the application of the system of thepresent invention to spark plugs of a motor vehicle.

FIG. 4 is a schematic diagram of the optional power boost voltageregulator as used with the power supply.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown the ignition system 10 in accordancewith the preferred embodiment of the present invention. The ignitionsystem 10 includes a pair of functional groups. The first functionalgroup 12 is the power boost voltage regulator circuit. The secondfunctional group 14 is the output section. The second group 14 producesthe high-voltage AC output which is current limited by a ballastingreactance 16. Functional groups 12 and 14 act together so as toappropriately fire the spark plug 18. The functional group 12 is theinput power boost voltage regulator. Functional group 12 provides afeedback-controlled regulated DC supply to the second group 14 so as topermit the deployment of the present invention in engine systems withvarying input DC supply voltage voltages without adjustment. The inputpower boost voltage regulator 12 may additionally incorporate suitablemeans to reduce the output voltage when advisable and go into idle modeto reduce total module current draw from the engine primary DC powersupply.

The second functional group 14 produces the high-voltage AC outputsupplied to the spark plug 18. The ballasting resistance can be alumped-element capacitor, a lumped-element conductor, or a distributedinductance comprised of the leakage inductance of the output transformer22. In each such case, the intent and effect is to limit output currentonce an arc has been established across the spark plug electrodes 24permitting the output voltage to develop across the electrodes 24 whenthe open circuit (no arc) condition occurs.

One of the important benefits provided by this action is the property ofimmediately reestablishing the arc (typically within one quarter-cycleof the inverter frequency) should it be interrupted by conditions withinthe combustion chamber. The second functional group 14 also contains anelectronic spark timing pulse timer 25 for controlling the output. Thecircuit idles the output section when the control input 27 (EST input)is in the idle state and permits operation when the control input 27 isin the active state. The output control 25 can also contain circuitryintended to increase ignition timing accuracy. In the present invention,the second functional group 14 provides a DC-to-AC inverter withhigh-voltage at the output terminal 28 with output current limitinginherent in the characteristics of the circuit. It provides forsustaining the arc under all normal conditions for minimal electricalwear on the spark plug electrodes 24 within the cylinder. The output ofthe second functional group 14 (i.e. the oscillator timer) is set in thelower frequency (RF) band (1 kHz to 100 kHz) for the purposes of rapidelectrical action and minimization of size. The present invention, byutilizing high frequencies, can provide low mass, compactness, unitaryfunctionality, and rapid buildup of output voltage at turn-on with highelectrical efficiency during sustained arcing. The present inventionthus serves both distributor-type ignition systems and coil-near-plugsystems, or coil-on-plug systems.

The present invention utilizes a DC-to-AC high-voltage, high-frequencyinverter which is reactively current limited at the output in whichcontains a means by which the inverter may be activated and idled by alow voltage signal from the electronic spark timing circuit, such as isto be expected from an engine controller (whether analog or digital).The present invention also utilizes such controllable inverters with theaddition of a power boost supply whereby DC power to the controllableinverter may be constant over a specific range of primary supplyvoltages. The present invention can also include such controllableinverters with regulated power supplies wherein the regulated DC supplyto the inverter may be controlled over a specific range of DC outputvoltages by an external control input to the regulated supply. Thepresent invention can also comprise such controllable inverters with apower supply providing external control inputs wherein the power supplyis placed in an idle mode by means of an external control input so as toreduce the power drain from the primary power supply. The presentinvention also can comprise such controllable inverters with powersupplies providing external control inputs for voltage and/or shut downwith timers in the inverter controller circuitry such that time delay inthe initiation of the arc due to the time required for the inverter toreach full operation is minimized and/or compensated in order to provideaccurate ignition timing to the controlled engine. The present inventioncan also comprise controllable inverters with controllable regulatedpower supplies and timing-compensated inverter controllers havingadditional means whereby the voltage across the output terminals and/orthe current to the output terminals may be sensed while the inverter isin operation, as desired.

FIG. 2 is a detailed electrical schematic of the operation of theignition system of the present invention. It is to be understood thatthe specific circuit topology shown in FIG. 2, while sufficient toachieve the functionality of the present invention, should not limit, inanyway, the scope of the present invention with respect to the specificcircuitry, devices or circuit models contained therein. The presentinvention is, in each of the functions comprising its whole, isrealizable by way of several different circuit topologies, models andtheories of operation. It is further understood that the use of severaldifferent makes, models, technologies, and types of electroniccomponents in each of the crucial active-device positions in anyparticular circuit topology chosen can also achieve the desiredfunction.

Referring generally to FIG. 2, the ignition system 10 of the presentinvention is shown in schematic form. The ignition system of the presentinvention includes an output transformer 22. Output transformer 22 canbe a gapped magnetic ferrite ceramic core transformer configured so asto provide partial decoupling of the primary and secondary windings.This constitutes the output current limiting reactants in the form ofthe secondary winding 30 leakage inductance. The primary windings 32 and33 have a center tap 34 and switching transistors 36 and 38 connected toeach end terminal.

In general, and electronic spark timing (EST) control signal is providedby the engine controller which is conditioned and used to activate anRC-controlled mono-stable oscillator. This mono-stable oscillator 40 isused to control the timing of the electronic spark timing circuit 42along with the arc duration. The arc duration will be between 0.5milliseconds to 5 milliseconds. The same timing pulse from themono-stable oscillator 40 is then used to activate or enable a frequencyastable oscillator or timer circuit and enable a buffered FET gatedriver integrated circuit. As mentioned above, the second timer isconfigured as an astable oscillator that is configured to provide about1 kHz to 100 kHz (a 0 volt to 8 volt signal) and is used to provide afirst gate drive signal to the inverting input of the gate driverintegrated circuit 44. The first output of the gate driver integratedcircuit 44 is then used to drive the first FET 36. In addition, thisfirst gate drive output is then connected to the second inverting inputof the gate driver integrated circuit 44. This guarantees the necessaryout-of-phase gate drive timing to the second FET 38. The combination ofthese timers and gate driver integrated circuits are used to produce theswitching signals to the N channel enhancement mode switchingtransistors 36 and 38 from the gate drive bias resistors 46 and 48. Theprimary winding 32 is bridged by a capacitor 50 (external) so as to forma resonant tank circuit. This entire circuit is in the form of apush-pull inverter. The oscillator is disabled by means of the ESTmono-stable output returning to 0 volts at the end of the 0.5millisecond to 5 millisecond desired timing pulse.

At start-up, the oscillator 40 is commanded on by the enginecontroller's EST signal. The resonant tank having the capacitor 50 andthe primary winding 32 are driven or switched at a commanded frequencyto deliver maximum power to the output of the transformer 32. Amplitudeoscillation will continue as long as power and bias are available toswitching transistors 36 and 38. The push-pull inverter circuit is thusself-starting and self-sustaining. Specifically, referring to FIG. 2,power is initially provided through an EST input 52 toward a resistor54. Resistor 54 serves to level shift the input for the EST 42. As such,it serves as a voltage divider. Capacitor 56 is a filter capacitor forEST 42. Resistor 58 is for input current sinking to the EST 42. Avoltage transient suppression diode 60 is clamped to the eight voltpower supply output from the voltage regulator and serves to suppresstransients in the voltage being transmitted to the EST 42. An inputcapacitor 62 is provided along the pathway from the EST input 52 to thetrigger terminal of the EST 42. The mono-stable oscillator 40 willextend through pins 1 and 8 of the EST 42. The capacitor 64 and theresistor 66 establish the pulse duration for the alternating voltage foran arc of approximately 1.1 milliseconds. Resistor 68 and diode 70provide the input threshold trigger. Resistor 72 is a pull-up outputresistor to V_(dd) to provide output drive control. Ultimately, theenable pulse will emanate from the EST input 52 of the engine controlmodule (ECM) so as to be transmitted to the trigger pin of the EST 42.Capacitor and resistors 76, 78 and 80 are used to establish thefrequency of the base astable oscillator 82. The astable oscillator 82provides for a fixed frequency of between 1 kHz and 100 kHz. As such, itserves as a force push-pull inverter so as to force the frequencies ofthe present invention. The pin 4 of the timer driver IC 84 is providedan enable pulse from pin 3 that passes to the EST 42 output. Capacitor86 is a filter capacitor that is used to filter V_(dd) noise spikes.Enable pins 1 and 8 of the gate driver IC 44 are used to wake up thegate-driver IC 44 for about one millisecond pulse. The IC 44 is enabledby the pin 3 output of EST 42. Capacitors 88, 90 and 92 are storagecapacitors for the gate driver outputs. The power supply 94 will supplyeight volts of power from the voltage regulator circuit. As such, thegate-drive IC 44 can alternately bias the FETs 36 and 38 so as to drivethe respective primary windings 32 and 33. The capacitor 50, statedhereinbefore, helps to establish the resonate frequency. Ultimately, thevoltage will flow as a sinusoidal voltage to each of the primaries 32and 33. As a result, the transformer 22 will have the primaries 32 and34 biased alternately so as to create a high-voltage output from thesecondary 30. The system of the present invention assures that the FETs36 and 38 are not on at the same time. As such, each will have nearly a50% duty cycle during the arcing of the secondary 30 across the sparkplug gap 94.

The power supply initially comes from the battery 100. An optional powerboost voltage regulator 101 can be provided in association with thepower supply from battery 100. This power boost voltage regulator isshown in greater detail in FIG. 4. Filter capacitors 102, 104, and 106are provided so as to filter the transients from the battery voltage.The IC 108 is a voltage regulator that provides power to the timers ofthe EST 42 into the gate driver IC 44. Diode 110 is a blocking diode forreverse battery protection. Resistors 112 and 114 serve to set thevoltage reference to eight volts. Capacitor 116 is a storage capacitorfor the voltage regulator. Ultimately, the eight volts created by thevoltage regulator will be supplied to 118. Capacitor 120 is astorage/stability capacitor for the primary side voltage. Line 122 willextend to the center tap 34. Line 124 will extend to the secondary 30.The eight volts shown at 118 is supplied to the lower part of theschematic in those areas indicated as 8V.

In the present invention, a sensing secondary winding can be provided soas to permit feedback to an engine control unit with respect to thevoltage on the output secondary winding 30, if desired. The outputsecondary winding 30, if desired, can have its lower terminal connectedto a current sensor, such as a resistor and diode. This will permitfeedback to the engine controller unit with respect to the currentthrough the output secondary winding 30.

The power boost regulator voltage circuit, as shown as functional group12 of FIG. 1, and in the upper portion of the schematic of FIG. 2,provides a regulated voltage to the inverter in the range of 15 to 50volts, depending on the integrated circuit chosen and the ratio of thefeedback resistors. An input may be provided for reducing the regulatedvoltage with a proportional positive voltage. The amount of thereduction may be controlled by adjusting the value of the resistors. Acontrol input can be provided to put the switching regulator into anidle mode to the action of a pull-down transistor. The primary powerinlet from the battery is protected from load dump surges and spikes bysurge-absorbing diode.

In the present invention, is preferable that the voltage from thebattery be boosted so that the 5 to 15 volts from the battery turns into15 to 50 volts for the push/pull inverter. This would reduce the needfor a high turns ratio in the transformer 22. As such, with suchincrease in voltage, the size of the transformer 22 can be suitablyreduced.

The signal to the spark plugs from the EST 42 is a low voltage squarewave that can be configured, as desired, to turn the circuit on when thespark should fire and off when the engine does not require a spark. Thiscan be varied so as to provide longer “arc duration” during coldstarting and shorter during normal operation. The circuitry of thepresent invention can utilize a filter to block radio frequencies fromthe DC power supply. This can be a small ferrite toroid and a filtercapacitor.

The push-pull inverter used in the present invention, together with theprimary windings of the transformer, forms an oscillator with thewinding 32 during one-half cycle of the sine wave output and withwinding 33 during the other half of the sine wave output. Suitablecapacitors can be used so as to help set the desired oscillationfrequency, along with the primary inductance and secondary leakageinductance in order to deliver maximum power. The output of thetransformer 22 is a high-voltage sine wave that reaches at least +/−20kV (0-to-peak). The preferred operating frequency is in the range of 10kHz to 100 kHz.

The transformer 22 can take various shapes. One preferred type oftransformer 22 would include a ferrite core (gapped in the center leg),a primary winding having eight turns center tap of 18 gauge magnet wire,and a section bobbin secondary having approximately 10,000 turns of 40gauge magnet wire. The transformer 22 can be potted in a high-voltagepotting material. The circuit associated with the transformer 22 can bepotted in the same shielded enclosure.

FIG. 3 is a diagrammatic illustration showing the ignition system of thepresent invention as used directly in association with spark plugs 200and 202. In FIG. 3, it can be seen that the transformer 204 is directlyconnected onto the spark plug 200. Similarly, the transformer 206 isdirectly connected onto the spark plug 202. An electrical line 208 willextend from the controller 210 to the transformer 204. Anotherelectrical line 212 will extend from the controller 210 to thetransformer 206. As such, the controller 210 can provide the necessarytiming signals to the transformers 204 in 206 for the firing of thespark plugs 200 and 202, respectively.

Similarly, the transformer 204 includes a sensor line 214 extending backto the controller 210. The transformer 206 also includes a sensor line216 extending back to the controller 210. As such, controller 210 canreceive suitable signals from the transformers 204 in 206 as to theoperating conditions of the spark plugs 200 and 202 for a propermonitoring of the output current output voltage of the secondarywinding. By providing this information, the controller 210 can besuitably programmed to optimize the firing of the spark plugs 200 and202 in relation to items such as engine temperature and fuelconsumption. The automotive battery 218 is connected by line 220 so asto provide power to the controller 210.

As can be seen in FIG. 3, unlike conventional ignition coils, the firingof each of the spark plugs 200 and 202 is carried out directly on thespark plugs. The engine controller 210 can be a microprocessor which isprogrammed with the necessary information for the optimization of thefiring of each of the spark plugs. The engine controller 210 can receiveinputs from the crankshaft or from the engine as to the specific time atwhich the firing of the combustion chamber of each of the spark plugs200 and 202 is necessary. Since each of the transformers 204 and 206 arelocated directly on the spark plugs 200 and 202, and since they operateat low frequencies, radio interference within the automobile iseffectively avoided. Suitable shielding should be applied to each of thetransformers 204 and 206 further guard against any RF interference.

Within the system of the present invention, the 12 volt input isnominally the voltage of battery 218. This can vary from 6 volts at coldcranking to 14.5 or 15 volts during normal operation. The output voltageand energy of the high-voltage transformer is proportional to the inputvoltage. As such, is necessary to provide enough voltage and energy with6 volts of input to start the vehicle during low voltage conditions,such as cold starting.

Referring to FIG. 4, the optional power boost voltage regulator 101, asillustrated in FIG. 2, is illustrated. This power boost voltageregulator 101 includes a switch regulator integrated circuit 266, aswitching transistor 268, and energy storage inductor 270, an inputfilter capacitor 272 and an output filter capacitor 274. The circuitprovides a regulated voltage to the inverter in the range of 15 to 50volts, depending on the integrated circuit 266 that is chosen and theratio of feedback resistors 276 and 278. An input 280 may be providedfor reducing the regulated voltage with a proportional positive voltage.The amount of the reduction may be controlled by adjusting the value ofthe resistor 282. A control input 284 is provided for putting the switchregulator integrated circuit 266 into an idle mode through the action ofpull-down transistor 286. The primary power inlet 288 from the batteryis protected from load dump surges and spikes by a surge-absorbing diode290.

In the present invention, would be preferable that the voltage from thebattery be boosted so that the 5 to 15 volts from the battery turns into15 to 50 volts for the inverter. This would reduce the need for a highturns ratio in the transformer. As such, with such an increase involtage, the size of the transformer can be suitably reduced.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof. Various changes in the details ofthe illustrated construction can be made within the scope of theappended claims without departing from the true spirit of the invention.The present invention should only be limited by the following claims andtheir legal equivalents.

We claim:
 1. An ignition system for an internal combustion enginecomprising: a power source; a transformer having a first primary windingand a second primary winding and a secondary winding, said first andsecond primary windings connected to said power source such that saidtransformer produces an alternating voltage output from said secondarywinding of between 1 kHz and 100 kHz and a voltage of at least 20 kv; aconnector extending from said secondary winding, said connector adaptedto connect with a terminal of a spark plug of the internal combustionengine; an electronic spark timing circuit cooperative with saidtransformer so as to activate and deactivate a voltage to said first andsecond primary windings; and a forced push-pull inverter cooperativewith said electronic spark timing circuit so as to directly fix afrequency of voltage to said first and second primary windings.
 2. Theignition system of claim 1, the fixed frequency being between 1 kHz and100 kHz.
 3. The ignition system of claim 1, said forced push-pullinverter comprising an astable oscillator.
 4. The ignition system ofclaim 1, further comprising: an inverting gate-driver IC cooperativewith said electronic spark timing circuit so as to transmit voltagerelative to a timing pulse of said electronic spark timing circuit; afirst field effect transistor connected to an output of said gate-driverIC, said first field effect transistor being switchable so as totransmit the alternating voltage to said first primary winding; and asecond field effect transistor connected to an output of saidgate-driver IC, said second field effect transistor being switchable soas to transmit the alternating voltage to said second primary winding.5. The ignition system of claim 1, said alternating voltage output ofsaid secondary winding being a spark having a continuous arc duration ofbetween 0.5 millisecond and 5 milliseconds.
 6. The ignition system ofclaim 1, further comprising: a voltage regulator circuit electricallyconnected between said power source and said electronic spark timingcircuit so as to step down voltage from said power source.
 7. Theignition system of claim 6, said voltage regulator establish a referencevoltage of approximately 8 volts.
 8. The ignition system of claim 4,said gate-driver IC inverting voltage so as to cause said first fieldeffect transistor and said second field effect transistor to biasalternately.
 9. The ignition system of claim 1, further comprising: atransient voltage suppressor electrically connected between said powersource and said electronic spark timing circuit.
 10. The ignition systemof claim 1, said power supply comprising: a battery having a voltagebetween 5 volts and 15 volts.
 11. An ignition system for an internalcombustion engine comprising: a power source; a transformer having afirst primary winding and a second primary winding and a secondarywinding, said first and second primary windings connected to said powersource such that said transformer produces an alternating voltage outputfrom said secondary winding of between 1 kHz and 100 kHz and a voltageof at least 20 kv; a connector extending from said secondary winding,said connector adapted to connect with a terminal of a spark plug of theinternal combustion engine; an electronic spark timing circuitcooperative with said transformer so as to activate and deactivate avoltage to said first and second primary windings, said electronic sparktiming circuit passing a square wave of voltage to said electronic sparktiming circuit, said electronic spark timing circuit producing a voltagepulse off of a falling edge of the square wave.
 12. The ignition systemof claim 11, said square wave ranging from 0 volts to 5 volts, a sparkbeing generated to said secondary winding from said electronic sparktiming circuit when the square wave falls from 5 volts to 0 volts. 13.An ignition system for an internal combustion engine comprising: a powersource; a transformer having a first primary winding and a secondprimary winding and a secondary winding, said first and second primarywindings connected to said power source such that said transformerproduces an alternating voltage output from said secondary winding ofbetween 1 kHz and 100 kHz and a voltage of at least 20 kV; a connectorextending from said secondary winding, said connector adapted to connectwith a terminal of a spark plug of the internal combustion engine; anelectronic spark timing circuit cooperative with said transformer so asto activate and deactivate voltage to said first and second primarywindings; a forced push-pull inverter cooperative with said electronicspark timing circuit so as to fix a frequency of voltage to said firstand second primary windings, said electronic spark timing circuitpassing a square wave of voltage to said electronic spark timingcircuit, said electronic spark timing circuit producing a voltage pulseoff of a falling edge of the square wave; an inverting gate-driver ICcooperative with said electronic spark timing circuit so as to transmitvoltage relative to a timing pulse of said electronic spark timingcircuit; a first field effect transistor connected to an output of saidinverting gate-driver IC, said first field effect transistor beingswitchable so as to transmit the alternating voltage to said firstprimary winding; and a second field effect transistor connected to anoutput of said inverting gate-driver IC, said second field effecttransistor being switchable so as to transmit the alternating voltage tosaid second primary winding.
 14. The ignition system of claim 13, saidalternating voltage output of said secondary winding being a sparkhaving a continuous arc duration of between 0.5 millisecond and 5milliseconds.
 15. The ignition system of claim 13, further comprising: avoltage regulator circuit electrically connected between said powersource and said electronic spark timing circuit so as to step downvoltage from said power source.
 16. The ignition system of claim 13,said gate-driver IC inverting voltage so as to cause said first fieldeffect transistor and said second field effect transistor to biasalternately.
 17. The ignition system of claim 13, said power supplycomprising: a battery having a voltage of between 5 volts and 15 volts.